Identification of Fibronectin-Binding Proteins inMycoplasma gallisepticumStrain R

Abstract

We have determined that virulent Mycoplasma gallisepticum strain R low is capable of binding the extracellular matrix protein fibronectin. Fibronectin was found to be present in M. gallisepticum R low protein extracts by Western blotting and peptide sequencing. Mycoplasma gallisepticum R high , the attenuated, high-passage derivative of R low , is deficient in this ability. MGA_1199, the M. gallisepticum homologue of the cytadherenceassociated protein P65 from Mycoplasma pneumoniae, and MGA_0928, the M. gallisepticum homologue of the M. pneumoniae cytoskeletal protein HMW3, were identified as fibronectin-binding proteins. Peptides from the regions of MGA_1199 and MGA_0928 exhibiting the highest degree of homology with known fibronectinbinding proteins were shown to bind the gelatin/heparin-binding domain of fibronectin. MGA_1199 and MGA_0928 were shown to be absent and aberrant, respectively, in R high , explaining its lack of fibronectinbinding capability. Consistent with its M. pneumoniae counterpart, MGA_1199 (renamed PlpA) was demonstrated to be surface exposed, despite a lack of classical membrane-spanning domains. Due to its demonstrated topology and the strength of interaction between its binding peptide and fibronectin, we propose that PlpA functions as a fibronectin-binding protein in vivo and may possess atypical transmembrane domains.The avian pathogen Mycoplasma gallisepticum is known to cause chronic respiratory disease in chickens, infectious sinusitis in turkeys, and conjunctivitis in finches (23,33,45,49). The chronic nature of the infection and its effects on weight and egg production render it a pathogen of considerable economic importance to the poultry industry (49). Mycoplasma gallisepticum, together with Mycoplasma pneumoniae and Mycoplasma genitalium, is one of the three most prominent members of the M. pneumoniae phylogenetic cluster. Members of this cluster are pathogens that establish chronic infections and mediate attachment to the host epithelium via molecules present on a complex tip structure (33). The proteins that compose the tip structure, as well as a model for its assembly, have been described using M. pneumoniae (1,18,19).The virulence of strain R has been previously examined by comparing the virulent, low-passage strain (R low ) with the attenuated, high-passage strain (R high ) (29). Initial examination of the protein profiles of R low and R high indicated that three proteins were absent in R high . These proteins have been identified as the primary cytadhesin GapA, the cytadherence-related molecule CrmA, and a high-affinity transport protein, HatA (29,44). Complementation experiments with R high using wild-type gapA and crmA demonstrated that coexpression of GapA and CrmA is essential for cytadherence in M. gallisepticum (27); however, these attachment molecules were not able to completely restore virulence, suggesting that additional differences contribute to the attenuation of the high-passage isolate.With this in mind, we more closely examined the protein profiles of R l...

Characterization of pyruvate dehydrogenase subunit B and enolase as plasminogen-binding proteins in Mycoplasma pneumoniae

“…Within these multi-factorial processes, proteins on the mycoplasma surface play a central role in the host-pathogen interaction. In this context, binding to host ECM components is mediated by different mycoplasma molecules, such as adhesins and proteins of unknown function in Mycoplasma gallisepticum (Jenkins et al, 2007;May et al, 2006) and Mycoplasma hyopneumoniae (Burnett et al, 2006;Seymour et al, 2010), as well as proteins involved in protein synthesis and housekeeping enzymes in other species (Chen et al, 2011;Dallo et al, 2002;Dumke et al, 2011;Hoelzle et al, 2007). In addition to the described association of PDHB and elongation factor Tu of M. pneumoniae with human fibronectin (Dallo et al, 2002) and of GAPDH with human fibrinogen (Dumke et al, 2011), here we show that PDHB and enolase are binding partners of human plasminogen.…”

A Processed Multidomain Mycoplasma hyopneumoniae Adhesin Binds Fibronectin, Plasminogen, and Swine Respiratory Cilia

“…The C-terminal region of P116 binds fibronectin and plasminogen; to our knowledge, this is the first report identifying the capacity of a M. hyopneumoniae protein to bind these proteins. Fibronectin is a key component of the host extracellular matrix and fibronectin-binding proteins have been described in many other bacterial pathogens including Mycoplasma pneumoniae (40), Mycoplasma gallisepticum (30), and Mycoplasma penetrans (41). In this study we report M. hyopneumoniae as a bacterial pathogen capable of binding fibronectin.…”

Role of Mycoplasma pneumoniae glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in mediating interactions with the human extracellular matrix

“…The surfaceassociated protein MSG1 of the haemotrophic mycoplasma species Mycoplasma suis has been identified as GAPDH and contributes to the adhesion of the micro-organisms to erythrocytes (Hoelzle et al, 2007). In contrast, in the avian pathogen Mycoplasma gallisepticum, two non-glycolytic, cytadherence-associated proteins were found to act as binding partners of fibronectin (May et al, 2006). It should be noted that the GAPDH gene in mollicutes can show a high level of recombination as confirmed in Mycoplasma hominis (Søgaard et al, 2002).…”